A new approach to radio observations for forecasting shock arrival

0521247 - ÚFA 2020 BE eng A - Abstrakt
Jebaraj, I. C. - Magdalenic, J. - Scolini, C. - Podlachikova, T. - Dissauer, K. - Pomoell, J. - Rodriguez, L. - Kilpua, E. - Krupař, Vratislav - Veronig, A. - Poedts, S.
A new approach to radio observations for forecasting shock arrival.
16th European Space Weather Week. Brussels: Solar-Terrestrial Centre of Excellence (STCE), 2019.
[European Space Weather Week /16./. 18.11.2019-22.11.2019, Liège]
Institucionální podpora: RVO:68378289
Klíčová slova: geomagnetic storms * Coronal mass ejections * shock waves * radio emissions
Obor OECD: Fluids and plasma physics (including surface physics)
http://www.stce.be/esww2019/program/session_details.php?nr=6#

The disturbed geomagnetic conditions at the Earth, i.e. geomagnetic storms, are mainly driven by the Coronal mass ejections (CMEs) and associated shock waves. Therefore, tracking of CMEs and shocks and predicting their arrival at the Earth is an important scientific topic in the space weather. The shock associated radio emission, so called type II radio bursts, is frequently used to forecast the shock arrival to the Earth. The success of such a forecast is very variable. Forecasting results strongly depend on the source position of the radio emission relative to the CME (CME-flank or CME leading edge). Combination of the ground based and space-based radio observations provide us the unique opportunity to track shock waves starting from the Sun and to the inner heliosphere, and relate these observations with the CME observed in the white light. Herein we present rather novel technique so called radio triangulation, which surpasses the classically used 2D analysis of radio emissions and application of the 1D density models. Using stereoscopic radio observations, so called goniopolarimetric observations from the WAVES instrument onboard WIND, STEREO A and STEREO B, we can identify the source positions of interplanetary radio emission in the 3D space. The obtained results are then compared with the associated CME with the aim to understand if the CME-flank or the CME leading edge is the preferable type II source position. We study the CME/flare event on September 27/28, 2012. The GOES C3.7 flare was associated with the full-halo CME (first seen in the SOHO/LASCO C2 field of view at 23:47 UT) and white light shock observed by all three spacecraft STEREO A, STEREO B, and SOHO. The associated radio event is composed of a groups of type III bursts and two type II bursts with different starting time and frequency. The radio triangulation study shows that the first type II burst seem to be CME-driven, but the second type II occurs significantly higher in the solar corona than the CME, and has unclear origin. Since the radio source positions of the second type II are situated close to the nearby streamer, we believe that the shock wave – streamer interaction is the source of the second type II burst. In this event, using the second type II burst to predict the shock wave arrival at the Earth will be highly unreliable, showing large difference between the observed and predicted shock arrival.
Trvalý link: http://hdl.handle.net/11104/0305880